In general, the type of communication port chiefly used for data transmission includes a Universal Asynchronous Receiver Transmitter (UART) and a Universal Serial Bus (USB).
The UART is a device for processing asynchronous serial communication. Each of computers includes the UART in order to manage serial ports, and each of internal modems includes the UART. More specifically, the UART provides a computer with an RS-232C interface so that the computer can communicate with a modem or other serial devices or exchange data with a modem or other serial devices.
Furthermore, the USB is a peripheral access interface standard jointly proposed by 7 companies including IBM, and an object of the USB is to commonize an interface for connecting peripheral to a personal computer. If such a USB is used, all the peripherals can be connected to a personal computer without separately configuring software or hardware when the peripherals are connected to the personal computer. Accordingly, there are advantages in that the number of ports can be significantly reduced, installation is simple, and the size of a portable computer can be reduced.
In a prior art, Recommended Standard-232C (RS-232C) performed only data transmission between a mobile phone and a personal computer, but was problematic in the transmission of a large amount of data and a transfer rate and in that data and power could not be transmitted at the same time. In order to solve such problems, data transmission and charging are performed using a USB port. However, there is a problem in that the charging time is increased compared to charging using a dedicated adaptor, that is, a DC converter, if power is supplied using a USB terminal.
In techniques related to charging using a USB data cable, there are conventional techniques regarding a USB data cable that automatically detects the type of power in order to prevent overcharge, a USB data cable capable of randomly determining a charging time in order to prevent overcharge, and a USB data cable connected to a dedicated adaptor, that is, a DC converter. However, in charging using the USB terminal of a PC the use of the USB terminal is inconvenient because the charging time is very long. In the case of the USB data cable connected to the adaptor, there is inconvenience in terms of portability because a dedicated adaptor needs to be carried.